Scientists document ‘virgin births’ of endangered sawfish in Florida

Scientists have documented in Florida a series of “virgin births,” reproduction without mating, in a critically endangered sawfish species pushed to the brink of extinction by over-fishing and habitat destruction.

Scientists say that for the first time the phenomenon called parthenogenesis has been seen in a vertebrate in the wild. They also say that some females may be resorting to asexual reproduction because smalltooth sawfish numbers are so low that mating opportunities may not exist

Parthenogenesis:

It is a type of asexual reproduction in which the offspring develops from unfertilized eggs.

In parthenogenesis, a female’s egg cell can develop into a baby without being fertilized by a male’s sperm cell.

In making an egg cell, a precursor cell divides into four cells. The one that eventually becomes the egg cell retains key cellular structures and the gel-like cytoplasm. The other three hold extra genetic material.

In parthenogenesis, one of those cells essentially acts as a sperm cell and fuses with the egg. This fertilized egg possesses about half the mother’s genetic diversity, a trait allowing parthenogenesis to be detected through genetic testing.

Smalltooth sawfish:

Also known as the wide sawfish, it is a sawfish of the family Pristidae.

It is found in shallow tropical and subtropical waters in coastal parts of the Atlantic, including the Mediterranean. Smalltooth sawfish are born and live for about three years in southwest Florida estuaries before moving into ocean coastal habitats.

The species is listed as critically endangered by the International Union for the Conservation of Nature Red List.

They have a flattened shark-shaped body and a long, flat snout with pairs of teeth on the side used to find, stun and kill prey. They grow up to 18 feet long.

Their population collapse follows habitat loss and unintentional over-fishing, being caught in nets targeting other species.